The present invention relates to a single chip data processor containing a DMA (direct memory access) controller and, more particularly, to a single chip data processor incorporating technologies suitably adapted to provide a DMA controller for use with a communication control unit (communication facility or communication adapter).
In a data processor (micro-controller) or in a system comprising data input/output devices, data may be transferred at high speed via a DMA controller between a main memory device (storage device) inside the system and an I/O device configured. An example of this DMA controller is the 82258 advanced direct memory access controller (ADMA) from Intel, a United States corporation. This ADMA is illustratively described in "Nikkei Data Processing and Microcomputer," a Japanese publication, the January 198, issue, MC1-153-401 through 413.
As shown in FIG. 4, the above-cited DMA controller has an address generation unit (ADU) that generates an address of the main storage device, a byte count unit (BCU), a channel command register (CCR), a control status register (CSR) and other components connected to an internal data bus. The entire DMA controller arrangement, along with its associated components, is controlled by a central control unit (CCU).